The present invention relates to an apparatus for regulating the inflow of fuel into an intake duct of an internal combustion engine.
In order to overcome well-known problems associated with conventional carburetor systems, electronically controlled systems for injecting fuel into intake ducts of internal combustion engines were developed in the past. These systems are structurally simple because the injectors can be fed under relatively low pressure. The use of such electronically controlled fuel injectors has expanded, particularly with respect to four-stroke engine applications because of the ability to vary the injection timing and the injection duration. While these characteristics are advantageous relative to four-stroke engines, they are far less advantageous relative to two-stroke internal combustion engines. As a matter of fact, in two-stroke engines, problems arise from the nature of the diagram of distribution of the operating strokes, and these problems persist both in indirect fuel injection systems and carburetor fuel systems. However, at least with the indirect fuel injection systems, one can meter and maintain relatively perfectly constant air-to-gas/fuel ratios which in carburetor systems tends to change in the direction of enrichment of the air/fuel admixture as engine revolution speed increases.
While one might consider utilizing electronic fuel injection systems with two-stroke engines, particularly because of the advantages of varying the injection timing and the injection duration, the peculiarity of two-stroke engines makes this less desirable than one might initially appreciate. For example, though the value of injected fuel per each engine revolution would be optimum immediately upon the engine leaving the production line, in very short operating time thereafter this optimum level of performance deteriorates due to normal wear in the fuel passages, changes in clearances, etc. which during the life of the engine alters the amount of intake air per each engine revolution.